A5004401332- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Particle Accelerators and Free-Electron Lasers
- Gyrotron and Vacuum Electronics Research
- Astro and Planetary Science
- Fusion materials and technologies
- Superconducting Materials and Applications
- GNSS positioning and interference
- Dust and Plasma Wave Phenomena
- Planetary Science and Exploration
- Laser-Plasma Interactions and Diagnostics
- Lightning and Electromagnetic Phenomena
- Earthquake Detection and Analysis
- Solar and Space Plasma Dynamics
- Microwave and Dielectric Measurement Techniques
- Atomic and Molecular Physics
- Particle physics theoretical and experimental studies
- Nonlinear Photonic Systems
- Electromagnetic Compatibility and Measurements
- Nuclear Physics and Applications
- Cold Atom Physics and Bose-Einstein Condensates
- High-Energy Particle Collisions Research
- Stellar, planetary, and galactic studies
Space Science Institute
2021-2023
Los Alamos National Laboratory
2006-2022
Los Alamos National Security (United States)
2013
Fermi National Accelerator Laboratory
1993-2003
Universities Research Association
2002
Lawrence Berkeley National Laboratory
1997
University of California, Berkeley
1997
University of Rochester
1996
Princeton Plasma Physics Laboratory
1982-1992
Princeton University
1983-1992
The Sloan Digital Sky Survey (SDSS) will provide the data to support detailed investigations of distribution luminous and nonluminous matter in universe: a photometrically astrometrically calibrated digital imaging survey π sr above about Galactic latitude 30° five broad optical bands depth g' ∼ 23 mag, spectroscopic approximately 106 brightest galaxies 105 quasars found photometric object catalog produced by survey. This paper summarizes observational parameters products SDSS serves as an...
The Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere collect spectra ≈106 galaxies, 100,000 quasars, 30,000 stars, serendipity targets. In 2001 June, SDSS released to general astronomical community its early data release, roughly 462 deg2 including almost 14 million detected objects 54,008 follow-up spectra. were collected in drift-scan mode five bandpasses (u, g, r, i, z); our 95% completeness...
We present photometric and spectroscopic observations of 15 high-redshift quasars (z > 3.6) discovered from ∼140 deg2 five-color (u', g', r', i', z') imaging data taken by the Sloan Digital Sky Survey (SDSS) during its commissioning phase. The are selected their distinctive colors in SDSS multicolor space. Four have redshifts higher than 4.6 = 4.63, 4.75, 4.90, 5.00, latter being highest redshift quasar yet known). In addition, two previously known z 4 objects were recovered data. all i* <...
Using a variational technique, set of coupled model equations for the mode conversion process near ion cyclotron frequency is derived. The system truncated to first order in Larmor radius but includes effects explicit gradients and poloidal field. From conservation rule extracted which ensures total energy provides an expression wave damping differential form. are integrated numerically standard cases fast waves incident from either low- or high-field sides layer. scaling processes discussed...
Experimental results from high-power neutral-beam-injection experiments on the Princeton Large Torus tokamak are reported. At highest beam powers (2.4 MW) and lowest plasma densities [${n}_{e}(0)=5\ifmmode\times\else\texttimes\fi{}{10}^{13}$ ${\mathrm{cm}}^{\ensuremath{-}3}$], ion temperatures of 6.5 keV achieved. The collisionality ${{\ensuremath{\nu}}_{i}}^{*}$ drops below 0.1 over much radial profile. Electron heating $\frac{\ensuremath{\Delta}{T}_{e}}{{T}_{e}}\ensuremath{\approx}50%$ has...
Recent experiments involving high-power radio-frequency heating of a tokamak plasma show strong suppression the sawtooth oscillation. A high-energy trapped-particle population is shown to have stabilizing effect on internal resistive kink mode. Numerical calculations are in reasonable agreement with experment.
Fusion neutron emission of 1.5 × 1014 neutrons · s−1 and 2 1013 neutrons/pulse has been observed for PLT deuterium discharges with up to 2.5 MW neutral-beam injection. The time evolution magnitude are consistent theoretical calculations the fusion reactions caused by energetic injected ions which confined slow down classically. factor-of-two accuracy in absolute calibration is major uncertainty comparison theory. Neutron sawtooth oscillations (⪅ 3%) can also be explained
Meteoroid impacts on spacecraft are known to cause mechanical damage, but their electrical effect systems not well characterized. Several reported anomalies suggestive of an failure associated with meteoroid impact. We present a theory explain plasma production and subsequent electric fields occurring when strikes spacecraft, ionizing itself part the spacecraft. This plasma, charge separation commensurate different specie mobilities, can produce strong electromagnetic pulse (EMP) at broad...
Effects of high-power ion-Bernstein-wave heating on the PLT tokamak plasmas have been investigated with up to 650 kW rf power coupled plasma. A significant improvement in deuterium particle confinement (as much as 300%) during has observed. Associated it, a longer injected-impurity-confinement time, reduced drift-wave turbulence activity, frequency shifts turbulence, and development large negative edge potential were The ion efficiency,...
Abstract In this paper, we first study the dynamics of hot shocks in air cylindrical geometry coupled to multiband radiation transport and detailed chemistry. The wide energy length scale ranges which are covered herein includes exceeds ones subsequent return strokes happening during lightning discharges. An emphasis is put on NO x production optical power emitted by strong as generated Joule heating from intense current flows. rate , useful for atmospheric global modeling, found be between...
Energetic electrons can be trapped in Earth's magnetic field, forming the radiation belts (also known as Van Allen Belts). These electrons, which originate from solar wind or a high-altitude nuclear explosion (HANE), have potential to damage satellites low-Earth orbit (LEO). For example, 1962, U.S. detonated device at an altitude of about 400 km Starfish experiment. The resulting enhancement disabled several within few months and energetic remained for up years. In order address this...
Recent discoveries in a helicon plasma show decrease equilibrium density as magnetic field strength is increased. This can be explained the framework of low frequency electrostatic instability. However, quiescent behavior sources has been hitherto accepted. To verify existence an instability, extensive measurements fluctuating quantities and losses function were implemented. Furthermore, theoretical model was developed to compare measurements. Theory measurement very good agreement; both...
We have made a direct determination of the diffusion rates in stored, coasting antiproton beam by observing decay associated with echoes longitudinal plane. The echoes, similar to those observed other fields physics, are generated sequential impulse excitation at harmonics revolution frequency. echo envelope follows characteristic response which, however, can be modified presence even very weak scattering process, permitting sensitive rate beam.
Coupling structures for lower hybrid current drive experiments have, until now, been smaller than a free space wavelength and have had correspondingly broad wavenumber spectrum. The paper reports the results of on PLT tokamak using 16-waveguide grill (2.2 wavelengths) which produces very narrow n∥ = k∥c/ω Experimental from are compared with three other grills less sharply defined n1 spectra. figure merit, , is approximately 40% higher coupler previously reported PLT, in spite larger...
A computational scheme is developed which permits tractable calculation of three-dimensional full-wave solutions to the Vlasov-Maxwell equations under typical ion cyclotron range frequencies (ICRF) experimental conditions. The method unique in that power deposition plasma determined via anti-Hermitian part a truncated warm dielectric operator, rather than as result an assumed phenomenological collision frequency. resulting computer code allows arbitrary variation density, temperature,...
Tritium is produced in deuterium discharges the Princeton Large Torus by reaction D($d$,$p$)T. These tritons undergo reactions D($t$,$n$)$^{4}\mathrm{He}$ creating 14-MeV neutrons which have been detected two independent techniques at a level of 1% 2.5-MeV from D($d$,$n$)$^{3}\mathrm{He}$. The magnitude neutron emission consistent with finite banana width, neoclassical predictions for confinement energetic tritons.
Measurements of the toroidal rotation speed vφ(r) driven by neutral beam injection in tokamak plasmas and, particular, simultaneous profile measurements vφ, Ti, Te, and ne, have provided new insights into nature anomalous transport tokamaks. Low-recycling heated with unidirectional exhibit a strong correlation among local diffusivities, χφ≊χi&gt;χe. Recent confirmed similar behavior broad-density L-mode plasmas. These results are consistent conjecture that electrostatic turbulence is...
$d$-$^{3}\mathrm{He}$ reactions have been observed in the Princeton Large Torus by detecting unconfined 14.7-MeV proton. Reaction rates as high 2\ifmmode\times\else\texttimes\fi{}${10}^{13}$ ${\mathrm{sec}}^{\ensuremath{-}1}$ resulting 60 W of fusion power were obtained 500-kW heating a $^{3}\mathrm{He}$ minority ion-cyclotron range frequencies to energies above 80 keV. The fusion-power multiplication about ${10}^{\ensuremath{-}4}$ is equal highest any controlled-fusion experiment.
When a wave packet composed of short wavelength lower hybrid modes traveling in an homogeneous plasma region encounters inhomogeneity, it can resonantly excite long whistler waves via linear mechanism known as mode conversion. An enhancement hybrid/whistler activity has been often observed by sounding rockets and satellites the presence density depletions (striations) upper ionosphere. We address here process conversion to waves, mediated striation, using scalar‐field formalism (in limit...
Abstract In this paper, we develop a model of electrical discharge in air for the simulation some processes involved lightning discharges, as return strokes and dart leaders. The is initiated by vertical field modeled using nonlinear R‐L‐C circuit model, with which attempt to simulate initiation, growth, radial expansion, decay discharges related lightning. This gas dynamic type includes also both detailed chemistry accurate radiation transport, described first part article. For certain...
We present results from MiniMax (Fermilab T-864), a small test/experiment at the Tevatron designed to search for production of disoriented chiral condensate (DCC) in $p - \bar p$ collisions $\sqrt{s} = 1.8$ TeV forward direction, $\sim 3.4 < \eta \sim 4.2$. Data, consisting $1.3 \times 10^6$ events, are analyzed using robust observables developed an earlier paper. The consistent with generic, binomial-distribution partition pions into charged and neutral species. Limits on DCC various models...
Radiation and charge-exchange losses in the PLT tokamak are compared for discharges with Ohmic heating only (OH), additional by neutral beams (NB) or RF ion cyclotron frequency range (ICRF). Spectroscopic, bolometric soft-X-ray diagnostics were used. The effects of discharge cleaning, vacuum wall gettering, rate gas inlet on radiation from OH plasmas correlation between plasma core edge temperatures discussed. – For neutral-beam injection dependence type (e.g. co-injection versus counter-...
When a meteoroid penetrates Earth's atmosphere, it forms high‐density ionized plasma column immersed in the ionosphere between approximately 70 and 140 km altitude. High‐power, large‐aperture (HPLA) radars detect nonspecular trails when VHF or UHF radio waves reflect off structures turbulent meteor trail. These persist from few milliseconds to many minutes return these is referred as range‐spread trail echoes. In this paper, we present analysis of detected with ALTAIR, which an HPLA radar...